挤压铸造碳纤维增强A356金属基复合材料凝固过程的研究

分析了挤压铸造制备ＣＦ／Ａ３５６复合材料的充填过程，研究了工艺参数对基体合金凝固组织的影响．实验结果表明，当预制件中纤维均匀分布时，存在三角形、正方形、六边形３种排列方式，其充填阻力Ｐ＝４．３２ＭＰａ．挤压铸造ＣＦ／Ａ３５６复合材料时，当浇注温度较高时，其凝固发生在整个浸渗过程结束之后，这是由于模具和纤维的激冷作用，而首先凝固的晶坯在浸渗过程中局部或完全重熔；基体合金初生α－Ａｌ相在纤维间隙中形核并逐渐向纤维表面长大；而共晶Ｓｉ相依附碳纤维表面形核并长大，当预制件预热温度高于基体熔点时，共晶Ｓｉ相包覆碳纤维表面长大．随着凝固冷却速率的降低，共晶Ｓｉ相形态发生从蠕虫状、细针状到片状或块状的转变，其尺寸由小到大变化．     

提高环境工程本科生毕业设计（论文）质量的几点思考

针对环境工程专业特点,结合多年的毕业设计（论文）的指导经验,本文从合理选题、科研课题的引入、文献阅读的强化、加强讨论、补充实习、计算机应用能力增强、毕业设计参考资料库建立等几个方面,提出了提高大学生毕业设计（论文）质量的一些方法措施。     

基于小波分析江苏种植业自然风险的度量

以波动概念来表示种植业自然风险,接着创造性地引入了现代数学的小波分析方法来测定种植业产量的主要趋势分量,得到江苏7种主要农作物变异率和变异系数.实证结果表明,从长远和总体来看,江苏的经济作物自然风险高于粮食作物的自然风险;4种粮食作物的风险由小至大的品种依次为稻谷、玉米、小麦、大豆;3种经济作物的风险由小到大的品种依次为棉花、油菜籽、花生.     

浅论我国民事诉讼费用制度的价值追求

任何审判都是需要耗费资源的,而民事诉讼费用就是解决诉讼成本在国家与当事人、当事人之间的分配和承担问题,因此民事诉讼费用制度是民事诉讼法中不可或缺的一项制度.文章主要讨论在当今法治时代,民事诉讼费用应该体现的三大价值--保障诉讼权的实现、实现经济合理性、保障司法机制的良性运行,这三点也可以看作是民事诉讼费用制度的本质特征.     

新型压缩空气储能风电系统膨胀助力控制

针对风能波动性和间歇性问题,提出了新型机械耦合式压缩空气储能风电系统.建立了风电系统膨胀助力模式混杂动态模型.提出了涡旋机柔性切入、切入后动态协调以及膨胀助力优化控制等三级膨胀助力控制策略,采用输入输出反馈线性化以及前馈控制等方法完成控制器设计.基于1,kW风电系统试验平台验证了控制策略的有效性,提高了模式切换过渡过程和风能捕获的动态速度,有效降低了压缩气体的消耗,涡旋机全效率提升至46.7%.     

Pressure gradient evolution in the near-Earth magnetotail at the arrival of BBFs

Using in situ observations from THEMIS A, D and E during the 2008-2011 tail season, we present a statistical study of the evolution of pressure gradients in the near-Earth tail during bursty bulk flow （BBF） convection. We identified 138 substorm BBFs and 2,197 non-substorm BBFs for this study. We found that both the pressure and the Bz component of the magnetic field were enhanced at the arrival of BBFs at the spacecraft locations. We suggest that the increase of Bz during non-substorm BBFs is associated with flux pile-up. However, the much stronger enhancement of Bz during substorm BBFs implies the occurrence of magnetic field dipolarization which is caused by both the flux pile-up process and near-Earth current disruption. Furthermore, a bow-wave-like high pressure appears to be formed at the arrival of substorm BBFs, which is responsible for the formation of region-1-sense FACs. The azimuthal pressure gradient associated with the arrival of substorm BBFs lasts for about 5 min. The enhanced pressure gradient associated with the bow wave is caused by the braking and diversion of the Earthward flow in the inner plasma sheet. The results from this statistical study suggest that the braking and azimuthal diversion of BBFs may commonly create azimuthal pressure gradients, which are related to the forrnation of the FAC of the substorm current wedge.     

Insight into the covalent grafting of organic films onto carbon steel surfaces for protection

The novel use of p-nitrophenyldiazonium tetrafluoroborate salt(GG salt)as a protectant that is electrochemically grafted onto carbon steel has been investigated in0.05 mol L-1H2SO4and 5 wt%NaCl solutions using various corrosion monitoring techniques,such as electrochemical impedance spectroscopy,potentiodynamic polarisation,infrared spectra and scanning electron microscopy measurements.The electrochemical study reveals that this compound is a mixed inhibitor that predominantly controls the cathodic reaction.The surface-grafted film decreases the double-layer capacitance and obviously increases the charge transfer resistance relative to a bare carbon electrode.The values of inhibition effect remain nearly unchanged with an increase in temperature range of 298–318 K.The aryl diazonium is covalently bonded on the steel surface,causing a slight decrease in the apparent activation energy.Overall,the surface-grafted films exhibit excellent inhibition performance in acid and saline solutions within the studied temperature range.     

中国近代翻译理论研究发展脉络

中国的翻译研究经过古代时期的发展形成了基本的理论雏形。到鸦片战争以后,在翻译实践广泛开展的背景下,翻译理论研究也不断拓展、深化。近代中国的翻译研究表现为两条较为清晰的主线:翻译"科学论"的萌生与翻译"艺术论"的确立。从此,中国翻译研究者初步认识到翻译活动的两大基本属性,触及翻译活动的本质,翻译学在中国开始逐渐具备较为完整的轮廓。     

英语新课程资源的开发与利用

英语新课程改革的深入发展和情景教学的新理念,对新课程资源的开发与利用提出了进一步的要求。文章就教材不是唯一课程资源,教师是最重要的课程资源以及正确对待多媒体教学资源的开发和利用分别展开了论述,用详实的个例来说明这些资源怎样和学校课程有效地融为一体,既调动学生的积极性,又能使教师的教学策略得以充分的发挥。     

基于收益比较的监理公司串谋问题研究

运用收益比较分析的方法,通过分析监理公司在衡量是否与代建公司串谋两种情况下的收益大小,决定是否与之串谋的结论,从而也为政府阻止两者串谋提供决策依据。